The present invention relates to a dynamically tensioned orthosis configured to stabilize a human joint, for example, a human shoulder, elbow, wrist, hip, knee or ankle.
Over time, the joints of a human body invariably are subject to conditions that can lead to joint deterioration, immobility and pain. In some cases, a joint may undergo trauma; in other cases, with age and extensive use, a joint may sustain inherent joint laxity. In both of these cases, the joint can experience a disruption in static and dynamic support.
Human joints can be supported statically, dynamically and via negative pressure. To provide static support, a joint can include soft tissues such as muscles, ligaments, tendons and a capsule. A disruption of any of these static supports, either due to trauma or joint laxity may result in a decrease in the load sharing of those elements. As an example, where a joint ligament is compromised, it likely will be unable to effectively resist joint translation, which in turn can decrease joint stability.
A particular human joint that is prone to disruption due to its complex nature is the shoulder, which comprises the glenohumeral joint. Every year 4.5 million people seek help for shoulder pain, with 2 million seeking help for rotator cuff injuries. Nearly 250,000 people have rotator cuff surgery each year. Over 7.5 Million people go to their doctor for a shoulder problem annually, including shoulder and upper arm sprains and strains. Shoulder injury to the rotator cuff, labrum, or other muscles or tendons supporting the glenohumeral joint can lead to shoulder laxity (instability). If a patient has a weakened or unstable shoulder capsule that is not properly supported, it can lead to additional breakdown and injury.
With joint laxity, one will typically require rehabilitation, or, depending on the severity of the injury, surgery to fix the problem. Anterior/inferior instability is the most common problem (about 60%), and posterior instability (about 20%) is less common but does occur most frequently in football lineman. Multi-directional instability makes up the remaining 20% or so of cases.
The glenohumeral joint of the shoulder is invariably unstable due to the convex articulation of the humeral head with the concavity of the glenoid fossa. The humeral head is covered by less than a third of the glenoid fossa throughout the joint's entire range of motion. While the glenohumeral ligaments, labrum and capsule as well as the articular surface provide static support. These tissues can be disrupted due to traumatic injury or over time with inherent joint laxity. Accordingly, such compromised ligaments are unable to effectively resist joint translation, which decreases joint stability. Specifically, the inferior glenohumeral (GHL) (with its anterior and posterior bands), the superior GHL, and the coracohumeral GHL are all important components of the complex. When these respective ligaments are compromised, this can lead to anterior, posterior, inferior and/or multidirectional shoulder instabilities.
The most common cause of shoulder pain in athletes, and in particular young athletes, is shoulder instability and not, as frequently misdiagnosed some underlying rotator cuff injury, impingements or bursitis. Rotator cuff injuries for youth athletes are extremely rare, whereas instability is common. (Savatsky, Gary, MD. “Shoulder Instability.” Anterior Shoulder Instability (n.d.): n. pag. www.ossmc.com. 1 May 2006. Web. 9 Sep. 2015.)
To address shoulder instability, due to trauma, failed surgery or inherent joint laxity, or to protect or rehabilitate a successfully, surgically repaired shoulder, many healthcare providers resort to supporting the shoulder joint with an external orthopedic stabilization device. Such a device can provide external static, as well as dynamic, support to enable the individual to return to a previous level of function and hopefully reduce the risk of repeated injury. While there are a number of such devices in the market, many are complicated to use, have easily disrupted, misplaced or removed straps, and require a healthcare provider knowledgeable in the force vectors associated with particular instabilities to consistently install the device, particularly where the straps float over the shoulder. Further, most conventional shoulder braces do not address all forms of instability, for example, each of anterior/inferior instability, posterior instability, and straight compression laterally as well.